The invention relates to sidestream smoke reduction in burning cigarettes and the like. More particularly, the invention relates to a composition for use with cigarette paper, cigarette wrapper or wrapper for a cigar for treating and visably reducing sidestream smoke.
Various attempts have been made to reduce or eliminate sidestream smoke emanating from a burning cigarette. The applicant developed various approaches to cigarette sidestream smoke control systems as described in its Canadian patents 2,054,735 and 2,057,962; U.S. Pat. Nos. 5,462,073 and 5,709,228 and published PCT applications WO 96/22031; WO 98/16125 and WO 99/53778.
Other sidestream smoke control systems have been developed which use filter material or adsorptive material in the tobacco, filter or paper wrapper. Examples of these systems are described in U.S. Pat. Nos. 2,755,207 and 4,225,636; EP patent application 0 740 907 and WO 99/53778. U.S. Pat. No. 2,755,207 describes a low sidestream smoke cigarette paper. The cigarette paper on burning yields a smoke substantially free of obnoxious components. The cigarette paper is cellulosic material in fibre form. It has intimately associated therewith a finely divided mineral type siliceous catalyst material. The cigarette paper which is essentially non-combustible and refractory remains substantially unchanged during combustion of the cigarette paper and functions like a catalyst in modifying the combustion of the paper. Suitable siliceous catalysts include acid-treated clays, heat-treated montmorillonite and natural and synthetic silicates containing some hydrogen atoms which are relatively mobile. Suitable mixed silica oxides include silica oxides with alumina, zirconia, titania, chromium oxide and magnesium oxide. Other silicas include the oxides of silicon and aluminum in a weight ratio of 9:1 of silica to alumina.
U.S. Pat. No. 4,225,636 describes the use of carbon in the cigarette paper to reduce organic vapour phase components and total particulate matter found in sidestream smoke. In addition, the carbon results in a substantial reduction in visible sidestream smoke emitting from a burning cigarette. Activated carbon is preferred as the carbon source. The use of the activated carbon results in a slight drop in visible sidestream smoke. Up to 50% of the cigarette paper may be finely divided carbon. The carbon-coated papers may be used as the inner wrap for the tobacco rod in combination with a conventional cigarette.
European patent application 0 740 907 published Nov. 6, 1996 describes the use of zeolites in the tobacco of the cigarette to alter the characteristics of the mainstream smoke and in particular remove various components from the mainstream smoke such as some of the tars. The zeolite as provided in the tobacco, also apparently change the characteristics of the sidestream smoke. The zeolites used were of a particle size between 0.5 mm to 1.2 mm.
Published PCT patent application WO 99/53778 describes a non-combustible sheet of treatment material for reducing sidestream smoke emissions. The sheet is used as a wrap and is applied over conventional cigarette paper of a conventional cigarette. The wrap has a very high porosity to allow the cigarette to burn at or close to conventional free-burn rates while at the same time reduce visible sidestream smoke emissions. The non-combustible wrap includes non-combustible ceramic fibres, non-combustible activated carbon fibres as well as other standard materials used in making the wrap. The wrap also includes zeolites or other similar sorptive materials and an oxygen donor/oxygen storage metal oxide oxidation catalyst. The non-combustible wrap provides an acceptable degree of sidestream smoke control, however, due to the non-combustible nature of the wrap, a charred tube remains.
U.S. Pat. Nos. 4,433,697 and 4,915,117 describe the incorporation of ceramic fibres in a cigarette paper manufacture. U.S. Pat. No. 4,433,697 describes at least 1% by weight of certain ceramic fibres in the paper furnish in combination with magnesium oxide and/or magnesium hydroxide fillers to reduce visible sidestream smoke emanating from the burning cigarette. The furnish of fibre pulp, ceramic fibres and fillers are used to make a paper sheet on conventional paper making machines. The ceramic fibres may be selected from the group of polycrystalline alumina, aluminum-silicate and amorphous alumina. A filler of magnesium hydroxide or magnesium oxide is used and is coated on or applied to the fibres of the sheet.
Ito, U.S. Pat. No. 4,915,117 describes a non-combustible sheet for holding tobacco. The thin sheet is formed from ceramic materials which upon burning produces no smoke. The ceramic sheet comprises a woven or non-woven fabric of ceramic fibre or a mixture of paper and ceramics thermally decomposed at high temperature. The ceramic fibre may be selected from inorganic fibres such as silica fibre, silica-alumina fibre, alumina fibre, zirconia fibre, or alumino borosilicate and glass fibre. The ceramic sheet is formed by binding these materials by inorganic binders such as silica gel or alumina gel. The fibres are a preferably 1 to 10 micrometers in diameter.
Sol gels have been applied to conventional cigarette paper in order to reduce sidestream smoke, particularly sol gels made from a magnesium aluminate, calcium aluminate, titania, zirconia and aluminum oxide, as described in Canadian Patent 1,180,968 and Canadian Patent application 2,010,575. Canadian Patent 1,180,968 describes the application of magnesium hydroxide in the form of an amorphous gel as a cigarette paper filler component to improve ash appearance and sidestream smoke reduction. The magnesium hydroxide gel is coated on or applied to the fibres of the sheet of the cigarette paper. Canadian patent application 2,010,575 describes the use of gels produced by a solution gelation or sol-gel process for controlling the combustion of wrappers for smoking articles. The gels may be applied as coatings to paper fibres before the paper is formed into wrappers. The wrappers are useful for reducing visible sidestream smoke. The metal oxides for the sol gels may be aluminum, titanium, zirconium, sodium, potassium or calcium.
Catalysts have also been directly applied to cigarette paper, such as described in Canadian Patent 604,895 and U.S. Pat. No. 5,386,838. Canadian Patent 604,895 describes the use of platinum, osmium, iridium, palladium, rhodium and rhuthenium in the cigarette paper. These metals function as oxidation catalysts to treat vapours arising from combustion of the paper wrapper. Optimum catalytic effect has been provided by the metal palladium. The metal particles in a suitable medium are dispersed onto the face of a paper wrapper before it is applied to the cigarette.
U.S. Pat. No. 5,386,838 describes the use of a sol solution comprising a mixture of iron and magnesium as a smoke suppressive composition. The smoke suppressive composition is made by co-precipitating iron and magnesium from an aqueous solution in the presence of a base. The iron magnesium composition demonstrates high surface area of approximately 100 m2/g to approximately 225 m2/g when heated to a temperature between 100 and approximately 500xc2x0 C. The iron magnesium composition may be added to paper pulp which is used to make smoke suppressive cigarette paper. The iron magnesium composition apparently functions as an oxidation catalyst and reduces the amount of smoke produced by the burning cigarette. The catalyst may also be applied to the tobacco, for example, as described in U.S. Pat. No. 4,248,251, palladium, either in metallic form or as a salt, may be applied to the tobacco. The presence of palladium in tobacco reduces the polycyclic aromatic hydrocarbons in the mainstream smoke. Palladium is used in combination with an inorganic salt or nitric or nitrous acid. Such nitrates include lithium, sodium, potassium, rubidium, cesium, magnesium, calcium, strontium, lanthanum, cerium, neodymium, samarium, europium, gadolinium, terbium, dysprosium, erbium, scandium, manganese, iron, rhodium, palladium, copper, zinc, aluminum, gallium, tin, bismuth, hydrates thereof and mixtures thereof. Catalysts have also been used in tubes to reduce sidestream smoke such as described in published PCT application WO 98/16125.
Catalytic materials have been used in aerosol types of cigarettes which do not produce sidestream or mainstream smoke per se, but instead a flavoured aerosol. Examples of these aerosol cigarettes include those described in U.S. Pat. Nos. 5,040,551, 5,137,034 and 5,944,025, which use catalysts to provide the necessary heat generation to develop the aerosol. Such catalyst systems include oxides of cerium, palladium or platinum.
Although the prior art contemplates various sidestream smoke control systems, none of them have provided a system which effectively reduces sidestream smoke by simply incorporating active components in the combustible cigarette paper so that the cigarette burns like a normal cigarette without appreciably affecting cigarette taste. Accordingly, this invention provides a sidestream smoke control system which not only looks and tastes like a conventional cigarette but as well, in accordance with aspects thereof, ashes like a normal cigarette.
The invention provides for a significant reduction in sidestream smoke in its various applications. It has been found that such reduction in sidestream smoke can surprisingly be achieved by the combined use in a sidestream smoke treatment composition, of an oxygen storage and donor metal oxide oxidation catalyst and an essentially non-combustible finely divided porous particulate adjunct for the catalyst where said oxygen storage and donor metal oxide oxidation catalyst releases oxygen at free burn rate temperatures of the cigarette. This composition may be used with normal combustible cigarette paper to provide acceptable free-burn rates while minimizing or virtually eliminating visible sidestream smoke.
The adjunct for the catalyst may be any suitable essentially non-combustible particulate material such as clays, carbon materials such as milled carbon fibres, mineral based materials such as metal oxides and metal oxide fibres, ceramics such as milled ceramic fibres and high surface area porous particles. In this respect, the catalyst adjunct is most preferably an essentially non-combustible high surface area sorptive material such as activated carbon or zeolites. In a most preferred embodiment of the invention, the sorptive materials are zeolites and in particular, hydrophobic zeolites. The zeolites are especially preferred when used in combination with a cerium based catalyst.
The sidestream smoke treatment composition may be applied in various ways. The composition may be used as a filler in the manufacture of a cigarette paper, impregnated in a cigarette paper, or as a coating(s) or a layer(s) on the exterior and/or interior of a cigarette paper. The resultant low sidestream smoke treatment cigarette paper may have a range of porosities from very low porosities of about 0.5 Coresta units through to high porosity of about 1,000 Coresta units. Preferred porosities are usually less than 200 Coresta units and most preferred porosities are usually in the range of about 30 to 60 Coresta units. It is appreciated that such treated paper may be used as a multiple wrap. The treated paper may be applied as an outer wrap over a cigarette having conventional cigarette paper.
The sidestream smoke treatment composition may be applied as a coating on both or either side of a paper for a multiplexe2x80x94usually a doublexe2x80x94wrapped cigarette, or impregnated into the paper, or may be incorporated as a filler in the manufacture of the paper for single or multiple wraps of cigarette paper. In a double wrap arrangement, the sidestream smoke treatment composition may in one embodiment be sandwiched between two papers. In a further double wrap embodiment, the sidestream smoke treatment composition may be coated on the side of a paper adjacent the tobacco rod where different loadings of the composition sandwiched in between the two papers may be provided. In still a further double wrap embodiment, the sidestream smoke treatment composition may be coated onto both sides of the paper placed on the tobacco rod, where different loadings may be provided. A second paper may be used as a further wrap thereover. The cigarette treatment paper may have typical ashing characteristics which is a significant benefit over non-combustible cigarette tubes and wraps of the prior art. The treatment paper may be a conventional cellulose based cigarette paper which, with the treatment composition, surprisingly does not add to the sidestream smoke.
It has been found that in order to optimize sidestream smoke reduction, the catalyst and adjunct are used in combination. The two components may be co-mingled as a filler, for example, in the manufacture of cigarette paper. Alternatively, when used as a coating, the catalyst and the adjunct are also co-mingled, usually as a slurry, and applied as such. In respect of the preferred embodiments, and in particular, the combined use of cerium with zeolite, the materials may be applied as individual contacting thin layers to develop a multilayer coating. Such layers may be of a thickness usually less than that of conventional cigarette paper and due to their intimate contacting nature, function as though they were combined and co-mingled.
According to other aspects of the invention, a low sidestream smoke cigarette comprises a conventional tobacco rod and a combustible treatment paper having a sidestream smoke treatment composition for said rod, said treatment composition comprises in combination, an oxygen storage and donor metal oxide oxidation catalyst and an essentially non-combustible finely divided porous particulate adjunct for said catalyst where said oxygen storage and donor metal oxide oxidation catalyst releases oxygen at free burn rate temperatures of the cigarette.
According to an aspect of the invention, a low sidestream smoke cigarette comprising a conventional tobacco rod, and a combustible treatment paper having a sidestream smoke treatment composition comprising cerium oxide which functions both as an oxygen storage and donor metal oxide oxidation catalyst and an essentially non-combustible finely divided porous particulate adjunct for the catalyst where said oxygen storage and donor metal oxide oxidation catalyst releases oxygen at free burn rate temperatures of the cigarette. According to another aspect of the invention, a furnish composition for use in making a cigarette treatment paper for reducing sidestream smoke emitted from a burning cigarette comprises in combination an oxygen storage and donor metal oxide oxidation catalyst and an essentially non-combustible finely divided porous particulate adjunct where said oxygen storage and donor metal oxide oxidation catalyst releases oxygen at free burn rate temperatures of the cigarette.
According to a further aspect of the invention, a low sidestream smoke cigarette comprising a conventional tobacco rod, and a combustible treatment paper having a sidestream smoke treatment composition, said treatment composition comprising in combination, an oxygen storage and donor metal oxide oxidation catalyst and an essentially non-combustible zeolite adjunct for said catalyst where said oxygen storage and donor metal oxide oxidation catalyst releases oxygen at free burn rate temperatures of the cigarette.
According to a further aspect of the invention, a slurry composition for application to cigarette paper for reducing sidestream smoke emitted from a burning cigarette comprises in combination with an oxygen storage and donor metal oxide oxidation catalyst, an essentially non-combustible finely divided porous particulate adjunct for said catalyst where said oxygen storage and donor metal oxide oxidation catalyst releases oxygen at free burn rate temperatures of the cigarette.
According to another aspect of the invention, a combustible cigarette paper for use on a smokable tobacco rod of a cigarette for reducing sidestream smoke emitted from a burning cigarette, the cigarette treatment paper including a sidestream smoke treatment composition comprising in combination an oxygen storage and donor metal oxide oxidation catalyst and an essentially non-combustible finely divided porous particulate adjunct where said oxygen storage and donor metal oxide oxidation catalyst releases oxygen at free burn rate temperatures of the cigarette.
According to another aspect of the invention, a method for reducing sidestream smoke emitted from a burning cigarette, comprises treating sidestream smoke with a treatment composition carried by a combustible cigarette paper, said treatment composition comprising in combination, an oxygen storage and donor metal oxide oxidation catalyst and an essentially non-combustible finely divided porous particulate adjunct for said catalyst where said oxygen storage and donor metal oxide oxidation catalyst releases oxygen at free burn rate temperatures of the cigarette.
According to another aspect of the invention, a low sidestream smoke cigarette comprising a conventional tobacco rod and a combustible cigarette paper having and a sidestream smoke treatment composition associated with the cigarette paper, wherein said treatment composition reduces sidestream smoke by greater than about 90%. For ease of description, whenever the term cigarette is used, it is understood to not only include smokable cigarettes but as well any form of wrapped smokable tobacco product, such as cigars, or the like. Whenever the term treatment paper is used, it is understood to encompass combustible wrappers and the like which may be used on cigarettes, cigars and the like. The wrapper may be used as a single layer of cigarette paper or multiple layer of cigarette paper. The wrapper may be applied as the sole layer of cigarette paper or as a wrap over conventional cigarette paper of a cigarette. The treatment paper may include as its substrate conventional cigarette paper or similar combustible product with a wide range of porosities. The conventional tobacco rod encompasses tobacco compositions normally used in smokable cigarettes. These rods are to be distinguished from tobacco components used in aerosol cigarette.